1. Technical Field
This invention relates to an ignition system, and more particularly, to an ignition system wherein each cylinder has more than one ignition plug for igniting the mixture of air and fuel.
2. Prior Art
There are known internal combustion engines with dual plugs for each cylinder. An associated distributor has two separate high voltage contacts per cylinder, i.e. one for each plug. Thus each spark plug in a cylinder is energized by a separate ignition system. The two ignition systems are required to guarantee that each spark plug gap will break down and fire upon triggering of the ignition module. A distributorless ignition system (DIS) similarly requires a duplicate ignition system. It would be desirable to provide simultaneous dual plug operation and eliminate one of the ignition systems. These are some of the problems this invention overcomes.
U.S. Pat. No. 4,177,782 issued to Yoshinari et al teaches an ignition system for an internal combustion engine having two spark plugs in each cylinder wherein each of the spark plugs is fired by one ignition coil. Separate output terminals of a secondary coil of the ignition coil are connected to each of the two plugs. For a distributorless ignition system this would require four double ended coils. For simplicity and reduced cost, it would be desirable to require only two double ended coils for a distributorless ignition system. If the teachings of this patent are used with a distributor, two high voltage post connections for each coil as well as two posts for each cylinder are required. Also, the patent does not teach the simultaneous firing of the two spark plugs in a cylinder.
U.S. Pat. No. 4,407,259 issued to Abo also teaches using two spark plugs. The patent teaches a plasma ignition systemm with a plurality of plasma ignition plugs to eliminate a mechanical distributor for sequentially distributing plasma ignition energy into each plasma ignition plug. When both of the spark plugs break down, only one of the plugs would receive the stored capacitive energy in the ignition system. Again, the patent does not teach particular circuitry for promoting simultaneous firing of two spark plugs in one cylinder.